Secure interface control high-level page management

ABSTRACT

A method is provided. The method is implemented by a secure interface control of a computer that prevents unauthorized accesses to locations in a memory of the computer. The secure interface control determines that a host absolute page is not previously mapped to a virtual page in accordance with securing the host absolute page and a host virtual page is not already mapped to an absolute page in accordance with securing the host absolute page.

BACKGROUND

The present invention relates generally to computer technology, and morespecifically, to secure interface control high-level page management.

Cloud computing and cloud storage provides users with capabilities tostore and process their data in third-party data centers. Cloudcomputing facilitates the ability to provision a virtual machine (VM)for a customer quickly and easily, without requiring the customer topurchase hardware or to provide floor space for a physical server. Thecustomer may easily expand or contract the VM according to changingpreferences or requirements of the customer. Typically, a cloudcomputing provider provisions the VM, which is physically resident on aserver at the provider's data center. Customers are often concernedabout the security of data in the VM, particularly since computingproviders often store more than one customer's data on the same server.Customers may desire security between their own code/data and the cloudcomputing provider's code/data, as well as between their own code/dataand that of other VMs running at the provider's site. In addition, thecustomer may desire security from the provider's administrators as wellas against potential security breaches from other code running on themachine.

To handle such sensitive situations, cloud service providers mayimplement security controls to ensure proper data isolation and logicalstorage segregation. The extensive use of virtualization in implementingcloud infrastructure results in unique security concerns for customersof cloud services as virtualization alters the relationship between anoperating system (OS) and the underlying hardware, be it computing,storage, or even networking hardware. This introduces virtualization asan additional layer that itself must be properly configured, managed andsecured.

In general, a VM, running as a guest under the control of a hosthypervisor, relies on that hypervisor to transparently providevirtualization services for that guest. These services include memorymanagement, instruction emulation, and interruption processing.

In the case of memory management, the VM can move (page-in) its datafrom a disk to be resident in memory and the VM can also move its databack out (page-out) to the disk. While the page is resident in memory,the VM (guest) uses dynamic address translation (DAT) to map the pagesin memory from a guest virtual address to a guest absolute address. Inaddition, the host hypervisor has its own DAT mapping (from host virtualaddress to host absolute address) for the guest pages in memory and itcan, independently and transparently to the guest, page the guest pagesin and out of memory. It is through the host DAT tables that thehypervisor provides memory isolation or sharing of guest memory betweentwo separate guest VMs. The host is also able to access the guest memoryto simulate guest operations, when necessary, on behalf of the guest.

SUMMARY

In accordance with one or more embodiments, a method is provided. Themethod is implemented by a secure interface control of a computer thatprevents unauthorized accesses to locations in a memory of the computer.The secure interface control determines that a host absolute page is notpreviously mapped to a virtual page in accordance with securing the hostabsolute page and a host virtual page is not already mapped to anabsolute page in accordance with securing the host absolute page. Thetechnical effects and benefits of one or more embodiments of theinvention herein can include prohibiting access to secure storage by allnon-secure guests and the hypervisor.

In accordance with one or more embodiments or the above methodembodiment, the secure interface control can mark the host absolute pageas secure.

In accordance with one or more embodiments or any of the above methodembodiments, the secure interface control can register the host absolutepage for use by the secure interface control, securely decrypt the hostabsolute page, subsequently un-register the host absolute page for useby the secure interface control, and register the host absolute page tothe secure domain.

In accordance with one or more embodiments or any of the above methodembodiments, the secure interface control can register the host virtualaddress with the associated host absolute page to create a host-addresspair for use by the secure entity, and check the host virtual addressesmatch on access by the secure entity.

In accordance with one or more embodiments or any of the above methodembodiments, the secure interface control can lock the host absolutepage for use by the secure interface control to prevent other calls tothe host absolute page. The technical effects and benefits of one ormore embodiments of the present invention described herein can includeguaranteeing no sharing of storage between secure guests, as storage isshared between a single secure guest and the hypervisor under control ofthe secure guest.

In accordance with one or more embodiments or any of the above methodembodiments, the secure interface control can unlock the host absolutepage to assign a secure guest domain loaded into the memory. Thetechnical effects and benefits of one or more embodiments of the presentinvention described herein can include guaranteeing no sharing ofstorage between secure guests, as storage is shared between a singlesecure guest and the hypervisor under control of the secure guest.

In accordance with one or more embodiments or any of the above methodembodiments, a secure entity can access a secure page that has beentransparently paged-in by an untrusted entity executing on the computerand is non-secure.

In accordance with one or more embodiments or any of the above methodembodiments, the untrusted entity can be a hypervisor, and the secureentity can be a secure guest. The technical effects and benefits of oneor more embodiments of the present invention described herein caninclude the hypervisor guaranteeing that for any given resident secureguest page, that the associated host absolute address is only accessiblethrough a single hypervisor (host) DAT mapping.

In accordance with one or more embodiments or any of the above methodembodiments, hardware presents a program interruption to the untrustedentity indicating a need for decryption of a secure guest page.

In accordance with one or more embodiments or any of the above methodembodiments, the untrusted entity can issue an import instruction thatprovides the host absolute page and the host virtual page.

In accordance with one or more embodiments or any of the above methodembodiments, the method can be implemented as a computer program productand/or a system.

Additional features and advantages are realized through the techniquesof the present disclosure. Other embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe invention. For a better understanding of the invention with theadvantages and the features, refer to the description and to thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments of the invention are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 depicts a table for zone security according to one or moreembodiments of the present invention;

FIG. 2 depicts virtual and absolute address spaces for performing DATaccording to one or more embodiments of the present invention;

FIG. 3 depicts a nested, multi-part DAT to support a virtual machine(VM) running under a hypervisor according to one or more embodiments ofthe present invention;

FIG. 4 depicts a mapping of secure guest storage according to one ormore embodiments of the present invention;

FIG. 5 depicts a system schematic of a dynamic address translation (DAT)operation according to one or more embodiments of the present invention;

FIG. 6 depicts a system schematic of a secure interface control memoryaccording to one or more embodiments of the present invention;

FIG. 7 depicts a process flow of an import operation according to one ormore embodiments of the present invention;

FIG. 8 depicts a process flow of an import operation according to one ormore embodiments of the present invention;

FIG. 9 depicts a process of a donated memory operation according to oneor more embodiments of the present invention;

FIG. 10 depicts a process flow of a transition of non-secure hypervisorpages to secure pages of a secure interface control according to one ormore embodiments of the present invention;

FIG. 11 depicts a process flow of a secure storage access made by thesecure interface control according to one or more embodiments of thepresent invention;

FIG. 12 depicts a process flow of access tagging by the secure interfacecontrol and by hardware according to one or more embodiments of thepresent invention;

FIG. 13 depicts a process flow of translations to support secure andnon-secure accesses by the program and by the secure interface controlaccording to one or more embodiments of the present invention;

FIG. 14 depicts a process flow of a DAT with secure storage protectionby the program and by the secure interface control according to one ormore embodiments of the present invention;

FIG. 15 depicts a process flow for secure interface control high-levelpage management according to one or more embodiments of the presentinvention;

FIG. 16 depicts a process flow for secure interface control high-levelpage management according to one or more embodiments of the presentinvention;

FIG. 17 depicts a cloud computing environment according to one or moreembodiments of the present invention;

FIG. 18 depicts abstraction model layers according to one or moreembodiments of the present invention;

FIG. 19 depicts a system according to one or more embodiments of thepresent invention; and

FIG. 20 depicts a node according to one or more embodiments of thepresent invention.

The diagrams depicted herein are illustrative. There can be manyvariations to the diagrams or the operations described therein withoutdeparting from the spirit of the invention. For instance, the actionscan be performed in a differing order or actions can be added, deletedor modified. Also, the term “coupled” and variations thereof describeshaving a communications path between two elements and does not imply adirect connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification.

DETAILED DESCRIPTION

One or more embodiments of the present invention provide an additionallayer of security, referred to herein as a secure interface control, tovirtual machines (VMs) executing on a host computer under control of auntrusted entity. Particularly, the secure interface control leveragesan efficient, lightweight trusted firmware interface between the secureentity (e.g., guest, VM, or container) and the untrusted entity (e.g.,an untrusted, non-secure entity, a host, hypervisor, or OS) to providethis additional security. The secure interface control maintains anduses a registered mapping between a host virtual address and a hostabsolute address of any secure page to allow the untrusted entity tocontinue to provide page management functions for these pages whilestill providing a high level of security. In this regard, the newinterface is used so the secure interface control and the untrustedentity can provide page management in a way that allows the untrustedentity to continue to manage secure guest pages without the secureinterface control maintaining shadow tables (and the high performancecost associated with that) while the secure interface control guaranteessecurity in these page mappings.

The technical effects and benefits of one or more embodiments of theinvention herein can include prohibiting access to secure storage by allnon-secure guests and the hypervisor. Further, technical effects andbenefits of one or more embodiments of the present invention describedherein can include the hypervisor guaranteeing that for any givenresident secure guest page, that the associated host absolute address isonly accessible through a single hypervisor (host) DAT mapping (that is,there is a single host virtual address that maps to any given hostabsolute address assigned to a secure guest); the hypervisor DAT mapping(host virtual to host absolute) associated with any given secure guestpage does not change while it is paged-in; and the host absolute pageassociated with any secure guest page is mapped for only a single secureguest. Furthermore, there is no sharing of storage between secureguests, as storage is shared between a single secure guest and thehypervisor under control of the secure guest.

A virtual machine (VM), running as a guest under the control of a hosthypervisor (e.g., an untrusted entity), relies on that hypervisor totransparently provide virtualization services for that guest. Theseservices can apply to any interface between a secure entity and anotheruntrusted entity that traditionally allows access to the secureresources by this other entity. As mentioned previously, these servicescan include, but are not limited to memory management, instructionemulation, and interruption processing. For example, for interrupt andexception injection, the hypervisor typically reads and/or writes into aprefix area (low core) of the guest. The term “virtual machine” or “VM”as used herein refers to a logical representation of a physical machine(computing device, processor, etc.) and its processing environment(operating system (OS), software resources, etc.). The VM is maintainedas software that executes on an underlying host machine (physicalprocessor or set of processors). From the perspective of a user orsoftware resource, the VM appears to be its own independent physicalmachine. The terms “hypervisor” and “VM Monitor (VMM)” as used hereinrefer to a processing environment or platform service that manages andpermits multiple VM's to execute using multiple (and sometimesdifferent) OS's on a same host machine. It should be appreciated thatdeploying a VM includes an installation process of the VM and anactivation (or starting) process of the VM. In another example,deploying a VM includes an activation (or starting) process of the VM(e.g., in case the VM is previously installed or already exists).

In order to facilitate and support secure guests (e.g., secure entity),a technical challenge exists where additional security is requiredbetween the hypervisor and the secure guests without relying on thehypervisor, such that the hypervisor cannot access data from the VM, andhence, cannot provide services in the way described herein.

The secure execution described herein provides a hardware mechanism toguarantee isolation between secure storage and non-secure storage aswell as between secure storage belonging to different secure users. Forsecure guests, additional security is provided between the “untrusted”non-secure hypervisor and the secure guests. In order to do this, manyof the functions that the hypervisor typically does on behalf of theguests need to be incorporated into the machine. A new secure interfacecontrol, also referred to herein as “UV”, is described herein to providea secure interface between the hypervisor and the secure guests. Theterms secure interface control and ultravisor may used interchangeablyherein. The secure interface control works in collaboration with thehardware to provide this additional security.

The secure interface control, in one example, is implemented ininternal, secure, and trusted hardware and/or firmware. For a secureguest or entity, the secure interface control provides theinitialization and maintenance of the secure environment as well as thecoordination of the dispatch of these secure entities on the hardware.While the secure guest is actively using data and it is resident in hoststorage, it is kept “in the clear” in secure storage. Secure gueststorage can be accessed by that single secure guest—this being strictlyenforced by the hardware. That is, the hardware prevents any non-secureentity (including the hypervisor or other non-secure guests) ordifferent secure guest from accessing that data. In this example, thesecure interface control runs as a trusted part of the lowest levels offirmware. The lowest level, or millicode, is really an extension of thehardware and is used to implement the complex instructions and functionsdefined for example in zAarchitecture® from IBM. Millicode has access toall parts of storage, which in the context of secure execution, includesits own secure UV storage, non-secure hypervisor storage, secure gueststorage, and shared storage. This allows it to provide any functionneeded by the secure guest or by the hypervisor in support of thatguest. The secure interface control also has direct access to thehardware which allows the hardware to efficiently provide securitychecks under the control of conditions established by the secureinterface control.

In accordance with one or more embodiments of the present invention, asecure-storage bit is provided in the hardware to mark a secure page.When this bit is set, the hardware prevents any non-secure guest orhypervisor from accessing this page. In addition, each secure or sharedpage is registered in a zone-security table and is tagged with asecure-guest-domain identification (ID). When the page is non-secure itis marked as such in the zone-security table. This zone-security tableis maintained by the secure interface control per partition or zone.There is one entry per host absolute page which is used by the hardwareon any DAT translation made by a secure entity to verify that the pageis only accessed by the secure guest or entity that owns it.

In accordance with one or more embodiments of the present invention, thesoftware uses an UV Call (UVC) instruction to request the secureinterface control to perform a specific action. For example, the UVCinstruction can be used by the hypervisor to initialize the secureinterface control, create the secure guest domain (e.g., secure guestconfiguration), and create the virtual CPUs within that secureconfiguration. It can also be used to import (decrypt and assign tosecure guest domain) and export (encrypt and allow host access to) asecure guest page as part of the hypervisor page-in or page-outoperations. In addition, the secure guest has the ability to definestorage shared with the hypervisor, make secure-storage shared, and makeshared-storage secure.

To provide security, when the hypervisor is transparently paging thesecure guest data in and out, the secure interface control, working withthe hardware, provides and guarantees the decryption and encryption ofthe data. In order to accomplish this, the hypervisor is required toissue new UVCs when paging the secure guest data in and out. Thehardware, based on controls setup by the secure interface control duringthese new UVCs, will guarantee that these UVCs are indeed issued by thehypervisor.

In this new secure environment, whenever the hypervisor is paging-out asecure page, it is required to issue a new convert from secure storage(export) UVC. The secure interface control, in response to this exportUVC, will 1) indicate that the page is “locked” by the UV, 2) encryptthe page, 3) set the page to non-secure, and, 4) reset the UV lock. Oncethe export UVC is complete, the hypervisor can now page-out theencrypted guest page.

In addition, whenever the hypervisor is paging-in a secure page, it mustissue a new convert to secure storage (import) UVC. The UV, or secureinterface control, in response to this import UVC, will 1) mark the pageas secure in the hardware, 2) indicate that the page is “locked” by theUV, 3) decrypt the page, 4) set authority to a particular secure guestdomain, and 5) reset the UV lock. Whenever an access is made by a secureentity, the hardware performs authorization checks on that page duringtranslation. These checks include 1) a check to verify that the pagedoes indeed belong to the secure guest domain which is trying to accessit and 2) a check to make sure the hypervisor has not changed the hostmapping of this page while this page has been resident in guest memory.Once a page is marked as secure, the hardware prevents access to anysecure page by either the hypervisor or by a non-secure guest VM. Theadditional translation steps prevent access by another secure VM andprevent remapping by the hypervisor.

Turning now to FIG. 1, a table 100 for zone security is generally shownin accordance with one or more embodiments of the present invention. Thezone-security table 100 shown in FIG. 1 is maintained by the secureinterface control and is used by the secure interface control andhardware to guarantee secure access to any page accessed by a secureentity. The zone-security table 100 is indexed by the host absoluteaddress 110. That is, there is one entry for each page of host absolutestorage. Each entry includes information that is used to verify theentry as belonging to the secure entity making the access.

Further, as shown in FIG. 1, the zone-security table 100 includes asecure domain ID 120 (identifies the secure domain associated with thispage); a UV-bit 130 (indicates that this page was donated to the secureinterface control and is owned by the secure interface control); adisable address compare (DA)-bit 140 (used to disable the host addresspair compare in certain circumstances such as when a secure interfacecontrol page that is defined as host absolute does not have anassociated host virtual address); a shared (SH)-bit 150 (indicates thatthe page is shared with the non-secure hypervisor) and a host virtualaddress 160 (indicates the host virtual address registered for this hostabsolute address, which is referred to as the host-address pair). Notethat a host-address pair indicates a host absolute and associated,registered host virtual address. The host-address pair represents themapping of this page, once imported by the hypervisor, and thecomparison guarantees that the host does not remap that page while it isbeing used by the guest.

Dynamic address translation (DAT) is used to map virtual storage to realstorage. When a guest VM is running as a pageable guest under thecontrol of a hypervisor, the guest uses DAT to manage pages resident inits memory. In addition, the host, independently, uses DAT to managethose guest pages (along with its own pages) when the pages are residentin its memory. The hypervisor uses DAT to provide isolation and/orsharing of storage between different VMs as well as to prevent guestaccess to hypervisor storage. The hypervisor has access to all of theguests' storage when guests are running in a non-secure mode.

DAT enables isolation of one application from another while stillpermitting them to share common resources. Also, it permits theimplementation of VMs, which may be used in the design and testing ofnew versions of OSs along with the concurrent processing of applicationprograms. A virtual address identifies a location in virtual storage. Anaddress space is a consecutive sequence of virtual addresses, togetherwith the specific transformation parameters (including DAT tables) whichallow each virtual address to be translated to an associated absoluteaddress which identifies that address with a byte location in storage.

DAT uses a multi-table lookup to translate the virtual address to theassociated absolute address. This table structure is typically definedand maintained by a storage manager. This storage manager transparentlyshares the absolute storage between multiple programs by paging out onepage, for example, to bring in another page. When the page is paged-out,the storage manager will set an invalid bit in the associated pagetable, for example. When a program tries to access a page that waspaged-out, the hardware will present a program interruption, oftenreferred to as a page fault, to the storage manager. In response, thestorage manager will page-in the requested page and reset the invalidbit. This is all done transparent to the program and allows the storagemanager to virtualize the storage and share it among various differentusers.

When a virtual address is used by a CPU to access main storage, it isfirst converted, by means of DAT, to a real address, and then, by meansof prefixing, to an absolute address. The designation (origin andlength) of the highest-level table for a specific address space iscalled an address-space-control element (ASCE) and defines theassociated address space.

Turning now to FIG. 2, example virtual address spaces 202 and 204 and anabsolute address space 206 for performing DAT are generally shown inaccordance with one or more embodiments of the present invention. In theexample shown in FIG. 2, there are two virtual address spaces: virtualaddress space 202 (defined by address space control element (ASCE) A208) and virtual address space 204 (defined by ASCE B 210). Virtualpages A1.V 212 a 1, A2.V 212 a 2, and A3.V 212 a 3 are mapped, by thestorage manager in a multi-table (segment 230 & page tables 232 a, 232b) lookup, using ASCE A 208, to absolute pages A1.A 220 a 1, A2.A 220 a2 and A3.A 220 a 3. Similarly, virtual pages B1.V 214 b 1 and B2.V 214 b2 are mapped in a two-table 234 & 236 lookup, using ASCE B 210, toabsolute pages B1.A 222 b 1 and B2.A 222 b 2, respectively.

Turning now to FIG. 3, an example of a nested, multi-part DATtranslation used to support a VM running under a hypervisor is generallyshown in accordance with one or more embodiments of the presentinvention. In the example shown in FIG. 3, guest A virtual address spaceA 302 (defined by guest ASCE (GASCE) A 304) and guest B virtual addressspace B 306 (defined by GASCEB 308) both reside in a shared host(hypervisor) virtual address space 325. As shown, virtual page A1.GV 310a 1, A2.GV 310 a 2, and A3.GV 310 a 3, belonging to guest A, are mapped,by the guest A storage manager, using GASCEA 304 to guest absolute pagesA1.HV 340 a 1, A2.HV 340 a 2, and A3.HV 340 a 3, respectively; virtualpage B1.GV 320 b 1 and B2.GV 320 b 2, belonging to guest B, are mapped,independently by the guest B storage manager, using GASCEB 308 to guestabsolute pages B1.HV 360 b 1 and B2.HV 360 b 2, respectively. In thisexample, these guest absolute pages map directly into the shared hostvirtual address space 325 and subsequently go through an additional hostDAT translation to a host absolute address space 330. As shown, hostvirtual addresses A1.HV 340 a 1, A3.HV 340 a 3, and B1.HV 360 b 1 aremapped, by the host storage manager using host ASCE (HASCE) 350 to A1.HA370 a 1, A3.HA 370 a 3, and B1.HA 370 b 1. Host virtual address A2.HV340 a 2, belonging to guest A, and B2.HV 360 b 2, belonging to guest B,are both mapped to the same host absolute page AB2.HA 380. This enablesdata to be shared between these two guests. During the guest DATtranslation, each of the guest table addresses is treated as a guestabsolute and undergoes an additional, nested host DAT translation.

Embodiments of the present invention described herein provide secureguest and UV storage protection. Access to secure storage by non-secureguests and the hypervisor is prohibited. The hypervisor provides that,for a given resident secure guest page, the following occurs. Theassociated host absolute address is only accessible through a singlehypervisor (host) DAT mapping. That is, there is a single host virtualaddress that maps to any given host absolute address assigned to asecure guest. The hypervisor DAT mapping (host virtual to host absolute)associated with a given secure guest page does not change while it ispaged-in. The host absolute page associated with a secure guest page ismapped for a single secure guest.

Sharing of storage between secure guests is also prohibited according toone or more embodiments of the present invention. Storage is sharedbetween a single secure guest and the hypervisor under control of thesecure guest. UV storage is secure storage and is accessible by thesecure control interface but not the guests/hosts. Storage is allocatedto the secure control interface by the hypervisor. According to one ormore embodiments of the present invention, any attempted violation ofthese rules is prohibited by the hardware and secure control interface.

Turning now to FIG. 4, an example of mapping of secure guest storage isgenerally shown in accordance with one or more embodiments of thepresent invention. FIG. 4 resembles FIG. 3, except that the example ofFIG. 4 does not allow for sharing of storage between secure guest A andsecure guest B. In the non-secure example of FIG. 3, both host virtualaddress A2.HV 340 a 2, belonging to guest A, and B2.HV 360 b 2,belonging to guest B, are mapped to the same host absolute page AB2.HA380. In the secure guest storage example of FIG. 4, host virtual addressA2.HV 340 a 2, belonging to guest A, maps to host absolute address A2.HA490 a, whereas B2.HV 360 b 2, belonging to guest B, maps to its ownB2.HA 490 b. In this example, there is no sharing between secure guests.

While the secure guest page resides on disk, it is encrypted. When thehypervisor pages-in a secure guest page, it issues a UV Call (UVC),which causes the secure control interface to mark the page as secure(unless shared), decrypt it (unless shared), and register it (in thezone-security table) as belonging to the appropriate secure guest (guestA, for example). In addition, it registers the associated host virtualaddress (A3.HV 340 a 3, for example) to that host absolute page(referred to as host-address pair). If the hypervisor fails to issue thecorrect UVC, it receives an exception when trying to access the secureguest page. When the hypervisor pages out a guest page, a similar UVC isissued which encrypts the guest page (unless shared) before marking theguest page as non-secure and registering it in the zone-security tableas non-secure.

In an example having five given host absolute pages K, P, L, M, and N,each of the host absolute pages are marked as secure by the securecontrol interface when the hypervisor pages them in. This preventsnon-secure guests and the hypervisor from accessing them. Host absolutepages K, P, and M are registered as belonging to guest A when thehypervisor pages them in; host absolute pages L and N are registered toguest B when paged-in by the Hypervisor. Shared pages, pages sharedbetween a single secure guest and the hypervisor, are not encrypted ordecrypted during paging. They are not marked as secure (allows access byhypervisor) but are registered with a single secure guest domain in thezone-security table.

In accordance with one or more embodiments of the present invention,when a non-secure guest or the hypervisor tries to access a page that isowned by a secure guest, the hypervisor receives a secure-storage access(PIC3D) exception. No additional translation step is required todetermine this.

In accordance with one or more embodiments, when a secure entity triesto access a page, the hardware performs an additional translation checkthat verifies that the storage does indeed belong to that particularsecure guest. If not, a non-secure access (PIC3E) exception is presentedto the hypervisor. In addition, if the host virtual address beingtranslated does not match the host virtual address from the registeredhost-address pair in the zone-security table, a secure-storage violation(‘3F’x) exception is recognized. To enable sharing with the hypervisor,a secure guest may access storage that is not marked as secure as longas the translation checks allow for access.

Turning now to FIG. 5, a system schematic 500 of a DAT operation isgenerally shown in accordance with one or more embodiments of thepresent invention. The system schematic 500 includes a host primaryvirtual address space 510 and a host home virtual address space 520,from which pages are translated (e.g., see host DAT translation 525;note that the dotted lines represent mapping through the DAT translation525) to a hypervisor (host) absolute address space 530. For instance,FIG. 5 illustrates the sharing of host absolute storage by two differenthost virtual address spaces and also the sharing of one of those hostvirtual addresses between not only two guests but, in addition, with thehost itself. In this regard, the host primary virtual address space 510and the host home virtual address space 520 are examples of two hostvirtual address spaces, each of which is addressed by a separate ASCE,the host primary ASCE (HPASCE) 591 and host home ASCE (HHASCE) 592,respectively. Note that all secure interface control storage (bothvirtual and real) is donated by the hypervisor and marked as secure.Once donated, the secure interface control storage can only be accessedby the secure interface control for as long as an associated secureentity exists.

As illustrated, the host primary virtual address space 510 includes aGuest A absolute page A1.HV, a Guest A absolute page A2.HV, a guest Babsolute page B1.HV, and a host virtual page H3.HV. The host homevirtual address space 520 includes a secure-interface-control virtualpage U1.HV, a host virtual page H1.HV, and a host virtual page H2.HV.

In accordance with one or more embodiments of the present invention, allsecure guest (e.g., secure Guest A & secure Guest B) storage isregistered, in the zone-security table described herein, as belonging toa secure guest configuration, and the associated host virtual address(e.g., A1.HV, A2.HV, B1.HV) is also registered as part of a host-addresspair. In one or more embodiments, all secure guest storage is mapped inthe host primary virtual space. In addition, all secure interfacecontrol storage is registered, also in the zone-security table, asbelonging to the secure interface control and may be furtherdifferentiated in the zone-security table based on the associated secureguest domain. In accordance with one or more embodiments of the presentinvention, UV virtual storage is mapped in host home virtual space andthe associated host virtual address is registered as part of thehost-address pair. In accordance with one or more embodiments, UV realstorage does not have an associated host virtual mapping, and the DA bitin the zone-security table (which indicates that the virtual addresscomparison is disabled) is set to indicate this. Host storage is markedas non-secure and is also registered in the zone-security table asnon-secure.

Thus, in the case where ‘guest absolute=host virtual,’ the hypervisor(host) primary DAT tables (defined by the HPASCE 591) translate thepages of the host primary virtual address space 510 as follows: theGuest A Absolute Page A1.HV is mapped to a Host Absolute A1.HA belongingto Secure Guest A; the Guest A Absolute Page A2.HV is mapped to a HostAbsolute A2.HA belonging to Secure Guest A; the Guest B Absolute PageB1.HV is mapped to a Host Absolute B1.HA belonging to Secure Guest B;and the Host Virtual Page H3.HV is mapped to a Host Absolute Page H3.HANon-Secure Host (and there is no host-address pair since it isnon-secure). Further, the hypervisor (host) home DAT tables (defined bythe HHASCE 592) translate the pages of the host home virtual addressspace 520 as follows: the Secure Interface Control Virtual Page U1.HV ismapped to a Host Absolute Page U1.HA defined as Secure UV Virtual; theHost Virtual Page H1.HV is mapped to a Host Absolute Page H1.HA definedas Non-Secure; and the Host Virtual Page H2.HV is mapped to a HostAbsolute Page H2.HA defined as Non-Secure. There is no host-address pairassociated with either H1.HA or H2.HA since they are non-secure.

In operation, if a secure guest tries to access a secure page assignedto the secure interface control, a secure-storage violation (‘3F’X)exception is presented by the hardware to the hypervisor. If anon-secure guest or the hypervisor tries to access any secure page(including those assigned to the secure interface control), asecure-storage access (‘3D’X) exception is presented by the hardware tothe hypervisor. Alternatively, an error condition can be presented forattempted accesses made to secure interface control space. If thehardware detects a mismatch in the secure assignment (e.g., the storageis registered in the zone-security table as belonging to a secure guestrather than to the secure interface control, or there is mismatch inhost-address pair being used with the registered pair) on a secureinterface control access, a check is presented.

In other words, the host primary virtual address space 510 includes hostvirtual pages A1.HV and A2.HV (belonging to secure guest A) and B1.HV(belonging to secure guest B), which map to host absolute A1.HA, A2.HA,and B1.HA, respectively. In addition, the host primary virtual addressspace 510 includes host (hypervisor) page H3.HV, which maps to hostabsolute H3.HA. The host home virtual space 520 includes two hostvirtual pages H1.HV and H2.HV, which map into host absolute pages H1.HAand H2.HA. Both the host primary virtual address space 510 and the hosthome virtual address space 520 map into the single host absolute 530.The storage pages belonging to secure guest A and secure guest B aremarked as secure and registered in the zone-security table 100 shown inFIG. 1 with their secure domains and associated host virtual addresses.The host storage, on the other hand, is marked as non-secure. When thehypervisor is defining the secure guests, it must donate host storage tothe secure interface control to use for secure control blocks needed insupport of these secure guests. This storage can be defined in eitherhost absolute or host virtual space and, in one example, specifically,in host home virtual space. Returning to FIG. 5, a host absolute pagesU1.HA and U2.HA Secure UV Absolute is secure-interface-control storagethat is defined as host absolute storage. As a result, these pages aremarked as secure and registered in the zone-security table 100 shown inFIG. 1 as belonging to the secure interface control and with anassociated secure domain. Since the pages are defined as host absoluteaddresses, there is no associated host virtual address so the DA-bit isset in the zone-security table 100.

After the translation, an example of the Hypervisor (Host) AbsoluteAddress Space 530 can be found in FIG. 6. The FIG. 6 a system schematic600 regarding a secure interface control memory is depicted according toone or more embodiments of the present invention. The system schematic600 illustrates a Hypervisor (Host) Absolute Address Space 630 includinga Host Absolute Page A2.HA Secure Guest A (for A2.HV); a Host AbsolutePage B1.HA Secure Guest B (for B1.HV); a Host Absolute Page H1.HANon-Secure (Host); a Host Absolute Page H2.HA Non-Secure (Host); a HostAbsolute Page U3.HA Secure UV Real (no HV mapping); a Host Absolute PageU1.HA Secure UV Virtual (for U1.HV); and a Host Absolute Page A1.HASecure Guest A (for A1.HV).

Turning now to FIG. 7, a process flow 700 for an import operation isgenerally shown according to one or more embodiments of the presentinvention. When a secure guest accesses a page that was paged-out by thehypervisor, a sequence of events such as that shown in the process flow700 occur in order to securely bring that page back in. The process flow700 beings at block 705, where the secure guest accesses the guestvirtual page. Since the page, for example, is invalid, the hardwarepresents a host page fault, indicated by program-interruption-code 11(PIC11), to the hypervisor (see block 715). The hypervisor, in turn,identifies an available non-secure host absolute page for this guestpage (see block 720) and pages-in the encrypted guest page to theidentified host absolute page (see block 725).

At block 730, the host absolute page is then mapped in the appropriate(based on host virtual address) host DAT tables. At block 735, thehypervisor host then re-dispatches the secure guest. At block 740, thesecure guest re-accesses the guest secure page. The page fault no longerexists but since this a secure guest access and the page is not markedas secure in the zone-security table 100 of FIG. 100, the hardwarepresents a non-secure-storage exception (PIC3E) to the hypervisor, atblock 745. This PIC3E prevents access by the guest to this secure pageuntil the necessary import has been issued. Next, the process flow 700proceeds to “A”, which is connected to FIG. 8.

Turning now to FIG. 8, a process flow 800 for performing an importoperation is generally shown in accordance with one or more embodimentsof the present invention. A well-behaved hypervisor (e.g., performing inan expected manner without errors), in response to the PIC3E, will issuean import UVC (see block 805). Note that at this point, a page to beimported is marked as non-secure and can only be accessed by thehypervisor, other non-secure entities, and the secure interface control.It cannot be accessed by secure guests.

As part of the import UVC, the trusted firmware acting as the secureinterface control checks to see if this page is already locked by thesecure interface control (see decision block 810). If it is, the processflow 800 proceeds to block 820. At block 820, a “busy” return code isreturned to the hypervisor that will, in response, delay (see block 825)and reissue the Import UVC (the process flow 800 returns to block 805).If the page is not already locked then, the process flow 800 proceeds todecision block 822.

At decision block 822, the secure interface control checks to see if thepage is a page which is shared with the non-secure hypervisor. If it isshared (the process flow 800 proceeds to decision block 824), the secureinterface control registers the host absolute address in thezone-security table with the associated secure guest domain, hostvirtual address and as shared. This page remains marked as non-secure.This completes the import UVC and the page is now available to beaccessed by the guest. Processing continues with the hypervisorre-dispatching guest (block 830) and the secure guest accessing the pagesuccessfully (block 835).

If the host virtual page to be imported is not shared with thehypervisor (the process flow 800 proceeds to block 840), the secureinterface control will mark the page as secure, so that the hypervisorcan no longer access the page. At block 845, the secure interfacecontrol locks the page, so that no other UVC can modify the page status.Once the lock is set (at block 850), the secure interface control willverify that the contents of the guest page did not change while it wasencrypted. If they did change then an error return code is returned tothe hypervisor, otherwise, the secure interface control will decrypt thesecure page.

At block 855, the secure interface control unlocks the page, allowingaccess by other UVCs, registers the page in the zone-security table, assecure and associated with the appropriate guest domain and host virtualaddress to complete the host-address HV->HA pair. This allows access bythe guest and completes the UVC.

Turning now to FIG. 9, a process flow 900 regarding a donated memoryoperation is generally shown in accordance with one or more embodimentsof the present invention. The process flow 900 begins at block 905,where a hypervisor issues a query-UVC to the secure interface control.At block 910, the secure interface control returns data (e.g., QueryUVC). This data can include an amount of base zone-specifichost-absolute storage required; an amount of basesecure-guest-domain-specific host-absolute storage required; an amountof variable secure-guest-domain-specific host-virtual storage requiredper MB; and/or amount of base secure-guest-CPU-specific host-absolutestorage required.

At block 915, the hypervisor reserves base host-absolute zone-specificstorage (e.g., based on a size returned by query UVC). At block 920, thehypervisor issues an initialization to the secure interface control. Inthis regard, the hypervisor can issue an initialize UVC that providesdonated storage for the UV control blocks that are needed to coordinatebetween the secure guest configurations for the entire zone. Theinitialize UVC specifies a base zone-specific storage origin.

At block 925, the secure interface control implements the initialization(e.g., initialize UVC) by registering donated storage to UV and markingas secure. For the initialize UVC, the secure interface control can markdonated storage as secure; assign some of that donated storage for thezone-security table; and register the donated storage in zone-securitytable for UV use with a unique secure-domain, but with no associatedsecure-guest-domain and as having no associated host-virtual addresspair.

At block 930, the hypervisor reserves storage (e.g., base and variablesecure-guest-domain-specific storage). For example, the hypervisorreserves base and variable (e.g., based on a size of secure-guest-domainstorage) secure-guest-domain-specific storage (e.g., a size returned bythe query UVC). At block 935, the hypervisor issues a createconfiguration to the secure interface control. In this regard, thehypervisor can issue a create-secure-guest-config UVC that specifiesbase and variable secure-guest-domain-specific storage origin. Further,the create-secure-guest-config UVC provides donated storage for the UVcontrol blocks that are needed to support this secure guestconfiguration.

At block 940, the secure interface control implements the createconfiguration (e.g., create-secure-guest-config UVC). For thecreate-secure-guest-config UVC, the secure interface control can markdonated storage as secure; register the donated storage in thezone-security table for UV use; and register the donated storage withthe associated secure-guest-domain. The donated base (host-absolute)storage is registered as having no associated host-virtual address pair.The donated variable (host-virtual) storage is registered with theassociated host-virtual address pair.

At block 945, the hypervisor reserves base secure-guest-CPU-specificstorage (e.g., a size returned by the query-UV). At block 950, thehypervisor specifies a storage origin. For instance, the hypervisorissues to the UV create-secure-guest-CPU that specifies a basesecure-guest-CPU-specific storage origin. At block 955, the secureinterface control implements the create-CPU (e.g.,create-secure-guest-CPU UVC). For the create-secure-guest-CPU UVC, thesecure interface control can mark donated storage as secure and registerdonated storage in the zone-security table for UV use, but with noassociated secure-guest-domain and as having no associated host-virtualaddress pair.

Turning now to FIG. 10, a process flow 1000 regarding a transition ofnon-secure hypervisor pages to secure pages of a secure interfacecontrol is generally shown in accordance with one or more embodiments ofthe present invention. In the process flow 1000, three hypervisor pagesare shown (e.g., a non-secure hypervisor Page A, a non-secure hypervisorPage B, and a non-secure hypervisor Page C).

The hypervisor (non-secure) Pages A, B and C can be accessed by anon-secure entity (including the hypervisor). Further, hypervisor(non-secure) Pages A, B and C are marked as non-secure (NS), along withregistered in a zone-security table (e.g., the zone-security table 100shown in FIG. 1) as non-secure and non-shared. At arrow 1005, aninitialize UVC is issued, which transitions Guest Page A to secureinterface control real storage page 1010 associated with an entire zone(UV2). The secure interface control real storage 1010 can be marked assecure, along with registered in a zone-security table (e.g., thezone-security table 100 shown in FIG. 1) as UV with no secure guestdomain and no hypervisor to host absolute (HV->HA) mapping. Instead itis registered with a unique UV2 secure domain and the DA-bit is setto 1. Note that the secure interface control real storage 1010 can beaccessed by the secure interface control as real.

From the hypervisor (Non-secure) Page B, at arrow 1025, create-SG-configor create-SG-CPU UVC is issued, which transitions this page to a secureinterface control real storage 1030 associated with a secure guestdomain (UVS). The secure interface control real storage 1030 can bemarked as secure, along with registered in a zone-security table (e.g.,the zone-security table 100 shown in FIG. 1) as UV with an associatedsecure guest domain and no hypervisor to host absolute (HV->HA) mapping(i.e., DA-bit=1). Note that the secure interface control real storage1010 can be accessed by the secure interface control as real on behalfof a secure guest domain.

From the hypervisor (non-secure) Page C, at arrow 1045, create-SG-configUVC is issued, which transitions this page to a secure interface controlvirtual storage 1050 associated with a secure guest domain (UVV). Thesecure interface control virtual storage 1050 can be marked as secure,along with registered in a zone-security table (e.g., the zone-securitytable 100 shown in FIG. 1) as UV with a secure guest domain andhypervisor to host absolute (HV->HA) mapping. Note that the secureinterface control virtual storage 1050 can be accessed as UV virtual onbehalf of a secure guest domain.

Turning now to FIG. 11, a process flow 1100 regarding a secure storageaccess made by the program or the secure interface control is depictedin accordance with one or more embodiments. This represents thesituation where the secure interface control is going to access gueststorage or secure interface control storage and must tag that accesscorrectly in order to allow the hardware to verify the security of thataccess. 1100 describes this tagging of storage accesses by the secureinterface control. The process flow 1100 begins at block 1110, where thesecure interface control determines whether it is making an access to asecure interface control storage.

If this is not an access to the secure interface control storage, thenthe process flow 1100 proceeds to decision block 1112 (as shown by theNO arrow). At decision block 1112, the secure interface controldetermines whether it is making an access to a secure guest storage. Ifthis is not an access to the secure guest storage, then the process flow1100 proceeds to proceeds to “B” (which is connected to process flow1200 of FIG. 12) which will use the default setting for non-secureaccesses. If this is an access to the secure guest storage, then theprocess flow 1100 proceeds to decision block 1113, where the secureinterface control determines if a default secure guest domain is beingused. If yes, then the process flow 1100 proceeds to proceeds to “B”(which is connected to process flow 1200 of FIG. 12) which will use thedefault setting for secure guest accesses. If no, then the process flow1100 proceeds to block 1114. At block 1114, an appropriate secure guestdomain is loaded into SG-secure-domain register (and proceeds to “B”,which is connected to process flow 1200 of FIG. 12).

If this is an access to the secure interface control storage, then theprocess flow 1100 proceeds to block 1120 (as shown by the YES arrow). Atblock 1120, the access is tagged as secure-UV (e.g., usesUV-secure-domain register).

The process flow 1100 then proceeds to decision block 1130, where thesecure interface control determines whether this is an access to UVVspace (e.g., SG-Config Variable Table). If it is an access to UVV space,then the process flow 1100 proceeds to block 1134 (as shown by the YESarrow). At block 1134, the access is tagged as virtual. At block 1136,an applicable secure guest domain is loaded into UV-secure-domainregister. At block 1138, DAT translation and access storage is ready tobegin. Returning to decision block 1130, if this is not an access to UVVspace, then the process flow 1100 proceeds to block 1140 (as shown bythe NO arrow). At block 1140, the access is tagged as real.

At decision block 1150, the secure interface control determines whetherthis is an access to UVS space (e.g., SG Configuration or CPU table). Ifthis is an access to UVS space, then the process flow 1100 proceeds toblock 1136 (as shown by the YES arrow). If this is not an access to UVSspace, then the process flow 1100 proceeds to block 1170 (as shown bythe NO arrow). This access would then be an access to UV2 space (e.g.,Zone-Security Table). At block 1170, a unique UV2 secure domain isloaded into UV-secure-domain register.

FIG. 12 depicts a process flow 1200 in accordance with one or moreembodiments of the present invention. When a guest is dispatched, SIEEntry firmware can indicate to the hardware that a guest is running(e.g., guest mode active) and can indicate whether the guest is secure.If the guest is secure, the associated secure guest domain can be loadedinto the hardware (e.g., in the SG-secure-domain register). When aprogram is accessing storage, the hardware can tag the access based onthe current state of the program at the time of the access. FIG. 12illustrates an example of this process in process flow 1200. At block1205, the hardware can determine whether the machine is currentlyrunning in guest mode and if not, can tag the access as being a hostaccess at block 1210 and as being a non-secure access at block 1215. Ifthe machine is running in guest mode at block 1205, the access can betagged as a guest access at block 1220 and further determine whether thecurrent guest is a secure guest at block 1225. If the guest is notsecure, the access can be tagged as non-secure at block 1215. If theguest is secure, the hardware can tag the guest as secure at block 1230,which can associate the secure guest with the SG-secure-domain registerthat was loaded when the secure guest was dispatched. For bothnon-secure and secure guests, a DAT status can be checked at block 1235.The access can be tagged as real at block 1240, if DAT is off. Theaccess can be tagged as virtual at block 1245, if DAT is on. Once theaccess is tagged as real at block 1240 with DAT off or as virtual atblock 1245 with DAT on, the hardware is ready to begin translation andaccess storage at block 1250, as further described in FIG. 13.

FIG. 13 depicts an example of translation done by the hardware tosupport both secure and non-secure accesses in process flow 1300 inaccordance with one or more embodiments of the present invention. Atblock 1305, the hardware can determine whether the access is tagged as aguest translation, and if so, and the access is virtual at block 1310,then guest DAT can be performed at block 1315. During guest DATtranslation, there can be nested, intermediate fetches for guest DATtables. The table fetches can be tagged as guest real and as secure ifthe original translation was tagged as secure. The table fetches canalso follow the translation process of process flow 1300. After theguest DAT is performed for an access tagged as guest virtual at block1315 and for any access tagged as guest real at block 1310 (virtual=No),guest prefixing and guest memory offset can be applied at block 1320. Atthe completion of the guest translation process, the resulting addresscan be tagged as host virtual and as secure if the original guesttranslation was tagged as secure at block 1325. The process 1300 cancontinue as for any access tagged as host virtual. If the originalaccess is a host access at block 1305, (guest=No) and virtual at block1330, then host DAT can be performed block 1335. Host table fetches canbe marked as non-secure at block 1335. After host DAT is performed atblock 1335, or if the original host access was tagged as real(virtual=No) at block 1330, then host prefixing can be applied at block1340. The resulting address can be a host absolute address at block1345.

FIG. 14 depicts an example of DAT translation with secure storageprotection that can be performed by the hardware in process flow 1400 inaccordance with one or more embodiments of the present invention.Continuing from block 1345 of FIG. 13, if a secure-UV access isidentified at block 1405, then the hardware can verify whether thestorage is registered as secure-UV storage at block 1410, and if not, anerror is presented at block 1415. A secure-UV access can be made by thesecure control interface when accessing UV storage. If the storage isregistered as secure-UV storage at block 1410, then protection checkscan continue as may be performed for any secure access except theUV-secure-domain-register (setup by the secure control interface beforemaking a secure-UV access) can be used as the specified secure domainfor the domain check at block 1420 where processing continues. Inaddition, any violation that is detected (entry point D) for a UV accessat block 1425 can be presented as an error at block 1430 rather than anexception to the hypervisor at block 1435 as is done for a secure guestviolation at block 1425 (Secure-UV=No).

For access that are not tagged as secure-UV accesses at block 1405, thehardware determines if the access is a secure guest access at block1440, and if not, and if the page is marked as secure at block 1445, anexception can be presented to the hypervisor at block 1435. Otherwise,if the access is not a secure guest access at block 1440 and the page isnot marked as secure at block 1445, then translation is successful atblock 1450.

If the access is a secure guest access at block 1440 or a secure-UVaccess to storage registered as secure-UV storage at block 1410, thehardware can check to make sure the storage is registered to the secureentity associated with the access at block 1420. If this is a secure-UVaccess, the specified secure-domain can be obtained from theUV-secure-domain register (loaded by the secure control interface basedon secure-UV storage being accessed) and for a secure-guest access, thespecified secure-domain is obtained from the SG-secure-domain register(loaded when the secure entity is dispatched). If the storage beingaccessed is not registered to the specified secure-domain at block 1420,then for secure-UV accesses at block 1425 an error is taken at block1430 and for secure-guest accesses at block 1425 (secure-UV=No) anexception is presented to the hypervisor at block 1435.

For secure accesses to storage at block 1440 and block 1410 that areregistered to the specified secure-domain at block 1420, if the virtualaddress check is disabled, i.e., the DA-bit=1 at block 1455 and theaccess is real at block 1460, then translation is complete at block1450. If, however, the DA-bit=1 at block 1455 but the access is virtualat block 1460 (real=No), then for secure-UV accesses at block 1425 anerror is taken at block 1430 and for secure-guest accesses at block 1425(secure-UV=No) an exception is presented to the hypervisor at block1435. If the DA-bit=0 at block 1455 and the access is a virtual accessat block 1475, then the hardware can determine if the host virtual tohost absolute mapping of the access matches that registered for thishost absolute address at block 1470. If so, then translation completessuccessfully at block 1450. If the mapping does not match at block 1470,then for secure-UV accesses at block 1425 an error is taken at block1430 and for secure-guest accesses at block 1425 (secure-UV=No) anexception is presented to the hypervisor at block 1435. If the DA-bit=0and the access is a real access at block 1475 (virtual=No) then forsecure-UV accesses at block 1425 an error is taken at block 1430 and forsecure-guest accesses at block 1425 (secure-UV=No) an exception ispresented to the hypervisor at block 1435; alternately, the translationmay complete successfully at block 1450. Any access by the I/O subsystemat block 1480 can check to see if the page is marked as secure at block1445 and if the page is secure, an exception can be presented to thehypervisor at block 1435; if the page is not marked as secure, thetranslation is successful at block 1450.

Various checks of storage registration and mapping can be managedcollectively through zone security table interface 1485. For example,blocks 1410, 1420, 1455, 1470, and 1475 can interface with a zonesecurity table that is associated with a same zone to manage variousaccesses.

As discussed above, DAT is used to map virtual storage to real storage.When a guest VM is running as a pageable guest under the control of ahypervisor, the guest uses DAT translation to manage pages resident inits memory and the host, independently, uses DAT translation to managethose guest pages (along with its own pages) when they are resident inits memory. The hypervisor uses its DAT translation to provide thenecessary isolation or sharing of storage between different VMs as wellas to prevent guest access to hypervisor storage. The hypervisor hasaccess to all of guest storage.

As discussed herein, one or more embodiments of the invention leveragean efficient, lightweight secure interface control interface betweensoftware and a machine to provide this additional security. In thisregard, that interface is used so the secure interface control andhypervisor can provide page management in a way that allows thehypervisor to continue to manage the secure guest pages while themachine (the secure interface control and hardware) guarantees securityin these page mappings.

In one or more embodiments, secure execution provides a hardwaremechanism to guarantee isolation between secure storage and non-securestorage as well as between secure storage belonging to different secureusers. For secure guests, additional security is provided between the“untrusted” hypervisor and the secure guests. To do this, many of thefunctions that the hypervisor typically performs on behalf of the guestsare incorporated into the machine via a control structure, called asecure interface control or a secure interface control (UV). The secureinterface control provides a secure interface between the hypervisor andthe secure guests. The secure interface control works in collaborationwith the hardware of the machine to provide this additional security.

The secure interface control is protection mechanism provided forvirtual machines (i.e., between the hypervisor and the secure guest)using virtual machine dispatches as the main point of transition or forvirtual executables using another boundary, for example, anaddress-space change, as the main point of translation.

The secure interface control (e.g., the ultravisor), in one example, isimplemented in internal, secure, and trusted firmware. For a secureguest or entity, the secure interface control provides theinitialization and maintenance of the secure environment as well as thecoordination of the dispatch of these secure entities on the hardware.While the secure guest is actively using data and it is resident in hoststorage, it is kept “in the clear” in secure storage. Secure storage canbe accessed by that single secure guest, which this being strictlyenforced by the hardware. That is, the hardware prevents any non-secureentity (including the hypervisor or other non-secure guests) ordifferent secure guest from accessing that data. In this example, thesecure interface control runs as a trusted part of the lowest levels offirmware. The lowest level has access to all parts of storage, such asits own secure UV storage, non-secure hypervisor storage, secure gueststorage, and shared storage. This access allows the secure interfacecontrol to provide any function needed by the secure guest or by thehypervisor in support of that guest. Also, the secure interface controlalso has direct access to the hardware, which allows the hardware toefficiently provide security checks under the control of conditionsestablished by the secure interface control.

The software uses an instruction call (e.g., UV Call (UVC) instruction)to request that the secure interface control perform a specific action.For example, the UVC instruction can be used by the hypervisor toinitialize the secure interface control, create the secure guest domain(e.g., secure guest configuration), and create the virtual CPUs withinthat secure configuration. The UVC instruction can also be used toImport (decrypt and assign to secure guest domain) and Export (encryptand allow host access) a secure guest page as part of the hypervisorpage-in or page-out operations. In addition, the secure guest has theability to define storage shared with the hypervisor, makesecure-storage shared, and make shared-storage secure.

These UVC commands are executed by the machine firmware similarly tomany other architected instructions. The machine does not enter a secureinterface control mode but instead the machine performs secure interfacecontrol functions in the mode in which it is currently running. There isno switch of contexts to handle these operations. This low overheadallows for closely-tied cooperation between the different layers of thesoftware, trusted firmware, and hardware in a way that minimizes andreduces complexity in the secure interface control while still providingthe necessary level of security.

To provide security, when the hypervisor is transparently paging thesecure guest data in and out, the secure interface control, working withthe hardware, provides and guarantees the decryption and encryption ofthe data. To accomplish this, the hypervisor is required to issue newUVCs when paging the secure guest data in and out. The hardware, basedon controls setup by the secure interface control during these new UVCs,will guarantee that these UVCs are indeed issued by the hypervisor.

The lightweight UVC design allows for the hypervisor page management toproceed without shadowing of the hypervisor tables by the secureinterface control and, therefore, without the large overhead to providethis shadowing. This is accomplished through the use of UV Callinstructions to transition a non-secure, encrypted page to a secure,decrypted page that is only allowed to be accessed by a singlesecure-guest domain. As part of this process, the secure interfacecontrol guarantees that for any secure guest page, the correspondingsecure host virtual page is mapped to a single host absolute page, thatonly a single host virtual address maps to any given secure hostabsolute address, and that the secure page belongs to a singlesecure-guest domain. In addition, the mapping of any secure host virtualaddress to a particular host absolute page is registered with the secureinterface control so that any change to that mapping would be detectedby the hardware and an exception presented.

In the secure environment described herein, whenever the hypervisor ispaging-out a secure page, it is required to issue a Convert to SecureStorage (Export) UVC. The UV, in response to this Export UVC, indicatesthat the page is “in transition” or “locked” by the UV, encrypts thepage, sets the page to non-secure, and resets the UV lock. Once theExport UVC is complete, the hypervisor can now page-out the encryptedguest page.

In addition, whenever the hypervisor is paging-in a secure page, it mustissue a Convert from Secure Storage (Import) UVC. The UV, in response tothis Import UVC, marks the page as secure in the hardware, indicatesthat the page is “in transition” or “locked” by the UV, decrypts thepage, and sets authority to a particular secure guest domain. Wheneveran access is made by a secure entity, the hardware performsauthorization checks on that page during translation. These checksinclude a check to verify that the page does indeed belong to the secureguest domain which is trying to access it and a check to make sure thehypervisor has not changed the host mapping of this page while this pagehas been resident in guest memory. Once a page is marked as secure, thehardware prevents access to any secure page by either the hypervisor orby a non-secure guest VM. The additional translation steps preventaccess by another secure VM and prevent remapping by the hypervisor.

In accordance with one or more embodiments, an additional programinterruption from the machine to indicate to the hypervisor that a new,additional step is provided. In this case, this additional step may bean Import of the guest page. The hardware prevents access of the page bythe secure guest until this additional step is completed by thehypervisor. This affords the advantage of minimizing the duplication ofmuch hypervisor work in the secure interface control by requiring thatthe secure interface control perform those steps which, for securityreasons, must be done in that secure environment. This approach,combined with the checks done during the Import UVC, eliminates the needfor the secure interface control to monitor and potentially shadow thehost DAT tables and the associated overhead and complexity.

In view of the above, operations for secure interface control high-levelpage management are discussed with respect to FIGS. 15-16. Turning nowto FIG. 15, a process flow 1500 for secure interface control high-levelpage management is depicted according to one or more embodiments of thepresent invention. The process flow 1500 overlays a secure entity (e.g.,VM or container) 1502, hardware 1504, an untrusted entity (e.g., anuntrusted, non-secure entity, a hypervisor, or an OS) 1506, and a secureinterface control 1508 to illustrate which operation is being performedby a component of the secure environment.

The process flow 1500 being at block 1510, where the secure entity 1502accesses a secure page that has been transparently paged-in by theuntrusted entity 1506 and is still encrypted (marked as non-secure). Atblock 1520, the hardware 1504 presents a program interruption to theuntrusted entity 1506 indicating a need for decryption of a secure guestpage. At block 1530, the untrusted entity 1506 issues an Import UVC(e.g., an import instruction). The Import UVC specifies a host absolutepage and a host virtual page as input parameters.

At block 1535, the secure interface control 1508, as part of theimplementation of the Import UVC, determines that the specified hostabsolute page is not already registered as mapped and locks hostabsolute page for use by the secure interface control 1508 (to preventother UVCs or secure entities access to the host absolute page). Notethat if a page that is being imported is already mapped (e.g., the hostvirtual page is already mapped to a different host absolute page or thehost absolute page already has a different host virtual page mapped toit), then an error is presented to the non-secure entity. At block 1540,the secure interface control 1508 marks the page (e.g., the hostabsolute page) as secure (to prevent access by non-secure entities).

At block 1550, the secure interface control 1508 determines that thehost virtual page is not already mapped to a secure absolute page andregisters the host virtual page for use by the secure interface control1508. Note that if a page that is being imported is already mapped(e.g., the host virtual page is already mapped to a different hostabsolute page or the host absolute page already has a different hostvirtual page mapped to it), then an error is presented to the non-secureentity.

At block 1560, the secure interface control 1508 securely decrypts thepage for eventual use by the guest. At block 1570, the secure interfacecontrol 1508 unlocks the host absolute page and registers the hostabsolute page as belonging to a secure particular guest domain and alsoregisters host virtual to host absolute mapping.

For instance, the secure interface control 1508 registers the hostabsolute page for use by the secure interface control 1508, securelydecrypts the host absolute page, subsequently un-registers the hostabsolute page for use by the secure interface control 1508, andregisters the host absolute page to the secure domain. Further, thesecure interface control 1508 registers the host virtual address withthe associated host absolute page to create a host-address pair for useby the secure entity, and checks the host virtual addresses match onaccess by the secure entity.

At block 1580, the untrusted entity re-dispatches the secure entity(e.g., guest or VM). At block 1590, the secure entity re-accesses the,now decrypted, page without exception.

Turning now to FIG. 16, a process flow 1600 for secure interface controlhigh-level page management is depicted according to one or moreembodiments of the present invention. The process flow 1600 overlays asecure entity (e.g., guest) 1602, hardware 1604, and an untrusted entity1606 to illustrate which operation is being performed by a component ofthe secure environment.

The process flow 1600 being at block 1610, where the secure entity(e.g., guest, VM, or container) 1602 accesses a secure virtual page. Forinstance, the secure entity 1602 has a secure domain ID n associatedtherewith and accesses a secure guest virtual page X.GV. At block 1620,the hardware 1604 performs DAT translation. For instance, the hardware1604 performs a DAT translation of guest virtual page X.GV to hostvirtual page X.HV and host absolute page X.HA.

Next, at decision block 1630, the hardware 1604 determines whether thesecure page is registered as belonging to the secure domain thatinitiated the secure access. For instance, the hardware 1604 determinesif secure page X.HA registered to secure domain n. If the secure page isnot registered to the secure domain n, then the process flow 1600proceeds to block 1650 (as shown by the NO arrow). At block 1650, thehardware 1604 presents a program exception to the untrusted entity(e.g., hypervisor) 1606. If the secure page is assigned to the secureguest domain, then the process flow 1600 proceeds to decision block 1670(as shown by the YES arrow).

At decision block 1670, the hardware 1604 determines whether theregistered host virtual address (corresponding to the registeredhost-address pair) matches the host-address pair obtained from the DATdone for the secure virtual access. For instance, the hardware 1604determines if a host virtual address registered with secure page X.HAmatches X.HV obtained by DAT. If the registered address does not matchthe DAT result, then the process flow 1600 proceeds to block 1650 (asshown by the NO arrow). At block 1650, the hardware 1604 presentsexception to the untrusted entity 1606. If the registered address doesmatch the DAT result, then the process flow 1600 proceeds to block 1690(as shown by the YES arrow). At block 1690, the hardware 1604 allowssecure entity access if all other protection checks allow for thisaccess.

It is to be understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, VMs, and services) that can be rapidlyprovisioned and released with minimal management effort or interactionwith a provider of the service. This cloud model may include at leastfive characteristics, at least three service models, and at least fourdeployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported, providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure that includes anetwork of interconnected nodes.

Referring now to FIG. 17, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 includes one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 17 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 18, a set of functional abstraction layersprovided by cloud computing environment 50 (FIG. 17) is shown. It shouldbe understood in advance that the components, layers, and functionsshown in FIG. 18 are intended to be illustrative only and embodiments ofthe invention are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and high-level page management 96. It isunderstood that these are just some examples and that in otherembodiments, the layers can include different services.

Turning now to FIG. 19, a system 1900 is depicted in accordance with oneor more embodiments of the present invention. The system 1900 includesan example node 10 (e.g., a hosting node) that is in direct or indirectcommunication with one or more client devices 20A-20E, such as via anetwork 165. The node 10 can be a datacenter or host server, of acloud-computing provider. The node 10 executes a hypervisor 12, whichfacilitates deploying one or more VMs 15 (15A-15N). The node 10 furtherincludes a hardware/firmware layer 11 that provides direct support forfunctions required by the VMs 15A-N and hypervisor 12 as well asfacilitates the hypervisor 12 in providing one or more services to theVMs 15. In contemporary implementations communication is providedbetween the hardware/firmware layer 11 and the hypervisor 12, betweenthe hardware/firmware layer 11 and the VMs 15, between the hypervisor 12and the VMs 15, and between the hypervisor 12 and the VMs 15 via thehardware/firmware layer 11. In accordance with one or more embodiments,of the present invention, a secure interface control is provided in thehardware/firmware layer 11, and the direct communication between thehypervisor 12 and the VMs 15 is eliminated.

For example, the node 10 can facilitate a client device 20A to deployone or more of the VMs 15A-15N. The VMs 15A-15N may be deployed inresponse to respective requests from distinct client devices 20A-20E.For example, the VM 15A may be deployed by the client device 20A, the VM15B may be deployed by the client device 20B, and the VM 15C may bedeployed by the client device 20C. The node 10 may also facilitate aclient to provision a physical server (without running as a VM). Theexamples described herein embody the provisioning of resources in thenode 10 as part of a VM, however the technical solutions described canalso be applied to provision the resources as part of a physical server.

In an example, the client devices 20A-20E may belong to the same entity,such as a person, a business, a government agency, a department within acompany, or any other entity, and the node 10 may be operated as aprivate cloud of the entity. In this case, the node 10 solely hosts VMs15A-15N that are deployed by the client devices 20A-20E that belong tothe entity. In another example, the client devices 20A-20E may belong todistinct entities. For example, a first entity may own the client device20A, while a second entity may own the client device 20B. In this case,the node 10 may be operated as a public cloud that hosts VMs fromdifferent entities. For example, the VMs 15A-15N may be deployed in ashrouded manner in which the VM 15A does not facilitate access to the VM15B. For example, the node 10 may shroud the VMs 15A-15N using an IBM zSystems® Processor Resource/Systems Manager (PRISM) Logical Partition(LPAR) feature. These features, such as PR/SM LPAR provide isolationbetween partitions, thus facilitating the node 10 to deploy two or moreVMs 15A-15N for different entities on the same physical node 10 indifferent logical partitions.

A client device 20A from the client devices 20A-20 e is a communicationapparatus such as a computer, a smartphone, a tablet computer, a desktopcomputer, a laptop computer, a server computer, or any othercommunication apparatus that requests deployment of a VM by thehypervisor 12 of the node 10. The client device 20A may send a requestfor receipt by the hypervisor via the network 165. A VM 15A, from theVMs 15A-15N is a VM image that the hypervisor 12 deploys in response toa request from the client device 20A from the client devices 20A-20 e.The hypervisor 12 is a VM monitor (VMM), which may be software,firmware, or hardware that creates and runs VMs. The hypervisor 12facilitates the VM 15A to use the hardware components of the node 10 toexecute programs and/or store data. With the appropriate features andmodifications the hypervisor 12 may be IBM z Systems®, Oracle's VMServer, Citrix's XenServer, Vmware's ESX, Microsoft Hyper-V hypervisor,or any other hypervisor. The hypervisor 12 may be a native hypervisorexecuting on the node 10 directly, or a hosted hypervisor executing onanother hypervisor.

Turning now to FIG. 20, a node 10 for implementing the teachings hereinis shown in according to one or more embodiments of the invention. Thenode 10 can be an electronic, computer framework comprising and/oremploying any number and combination of computing device and networksutilizing various communication technologies, as described herein. Thenode 10 can be easily scalable, extensible, and modular, with theability to change to different services or reconfigure some featuresindependently of others.

In this embodiment, the node 10 has a processor 2001, which can includeone or more central processing units (CPUs) 2001 a, 2001 b, 2001 c, etc.The processor 2001, also referred to as a processing circuit,microprocessor, computing unit, is coupled via a system bus 2002 to asystem memory 2003 and various other components. The system memory 2003includes read only memory (ROM) 2004 and random access memory (RAM)2005. The ROM 2004 is coupled to the system bus 2002 and may include abasic input/output system (BIOS), which controls certain basic functionsof the node 10. The RAM is read-write memory coupled to the system bus2002 for use by the processor 2001.

The node 10 of FIG. 20 includes a hard disk 2007, which is an example ofa tangible storage medium readable executable by the processor 2001. Thehard disk 2007 stores software 2008 and data 2009. The software 2008 isstored as instructions for execution on the node 10 by the processor2001 (to perform process, such as the processes described with referenceto FIGS. 1-19. The data 2009 includes a set of values of qualitative orquantitative variables organized in various data structures to supportand be used by operations of the software 2008.

The node 10 of FIG. 20 includes one or more adapters (e.g., hard diskcontrollers, network adapters, graphics adapters, etc.) thatinterconnect and support communications between the processor 2001, thesystem memory 2003, the hard disk 2007, and other components of the node10 (e.g., peripheral and external devices). In one or more embodimentsof the present invention, the one or more adapters can be connected toone or more I/O buses that are connected to the system bus 2002 via anintermediate bus bridge, and the one or more I/O buses can utilizecommon protocols, such as the Peripheral Component Interconnect (PCI).

As shown, the node 10 includes an interface adapter 2020 interconnectinga keyboard 2021, a mouse 2022, a speaker 2023, and a microphone 2024 tothe system bus 2002. The node 10 includes a display adapter 2030interconnecting the system bus 2002 to a display 2031. The displayadapter 2030 (and/or the processor 2001) can include a graphicscontroller to provide graphics performance, such as a display andmanagement of a GUI 2032. A communications adapter 2041 interconnectsthe system bus 2002 with a network 2050 enabling the node 10 tocommunicate with other systems, devices, data, and software, such as aserver 2051 and a database 2052. In one or more embodiments of thepresent invention, the operations of the software 2008 and the data 2009can be implemented on the network 2050 by the server 2051 and thedatabase 2052. For instance, the network 2050, the server 2051, and thedatabase 2052 can combine to provide internal iterations of the software2008 and the data 2009 as a platform as a service, a software as aservice, and/or infrastructure as a service (e.g., as a web applicationin a distributed system).

Embodiments described herein are necessarily rooted in computertechnology, and particularly computer servers that host VMs. Further,one or more embodiments of the present invention facilitate animprovement to the operation of computing technology itself, inparticular computer servers that host VMs, by facilitating the computerservers that host VMs to host secure VMs, in which even the hypervisoris prohibited from accessing memory, registers, and other such dataassociated with the secure VM. In addition, one or more embodiments ofthe present invention provide significant steps towards the improvementsof the VM hosting computing servers by using a secure interface control(also referred to herein as “UV”) that includes hardware, firmware(e.g., millicode), or a combination thereof to facilitate a separationof the secure VM and the hypervisor, and thus maintaining a security ofthe VMs hosted by the computing server. The secure interface controlprovides lightweight intermediate operations to facilitate the security,without adding substantial overhead to securing VM state duringinitialization/exit of VMs as described herein.

Embodiments of the invention disclosed herein may include system,method, and/or computer program product (herein a system) that implementsecure interface control high-level page management. Note that, for eachof explanation, identifiers for elements are reused for other similarelements of different figures.

Various embodiments of the invention are described herein with referenceto the related drawings. Alternative embodiments of the invention can bedevised without departing from the scope of this invention. Variousconnections and positional relationships (e.g., over, below, adjacent,etc.) are set forth between elements in the following description and inthe drawings. These connections and/or positional relationships, unlessspecified otherwise, can be direct or indirect, and the presentinvention is not intended to be limiting in this respect. Accordingly, acoupling of entities can refer to either a direct or an indirectcoupling, and a positional relationship between entities can be a director indirect positional relationship. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein.

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” may be understood to include any integer numbergreater than or equal to one, i.e., one, two, three, four, etc. Theterms “a plurality” may be understood to include any integer numbergreater than or equal to two, i.e., two, three, four, five, etc. Theterm “connection” may include both an indirect “connection” and a direct“connection.”

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one more other features,integers, steps, operations, element components, and/or groups thereof.

The descriptions of the various embodiments herein have been presentedfor purposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments. The terminologyused herein was chosen to best explain the principles of theembodiments, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method comprising: determining, by a secureinterface control of a computer that prevents unauthorized accesses tolocations in a memory of the computer, that a host absolute page is notpreviously mapped to a virtual page in accordance with securing the hostabsolute page; and determining, by the secure interface control, that ahost virtual page is not already mapped to an absolute page inaccordance with securing the host absolute page.
 2. The method of claim1, wherein the secure interface control marks the host absolute page assecure.
 3. The method of claim 2, wherein the secure interface controlregisters the host absolute page for use by the secure interfacecontrol, securely decrypts the host absolute page, subsequentlyun-registers the host absolute page for use by the secure interfacecontrol, and registers the host absolute page to the secure domain. 4.The method of claim 3, wherein the secure interface control registersthe host virtual address with the associated host absolute page tocreate a host-address pair for use by the secure entity, and checks thehost virtual addresses match on access by the secure entity.
 5. Themethod of claim 3, wherein the secure interface control locks the hostabsolute page for use by the secure interface control to prevent othercalls to the host absolute page.
 6. The method of claim 5, wherein thesecure interface control unlocks the host absolute page to assign asecure guest domain loaded into the memory.
 7. The method of claim 1,wherein a secure entity accesses a secure page that has beentransparently paged-in by an untrusted entity executing on the computerand is non-secure.
 8. The method of claim 7, wherein the untrustedentity is a hypervisor, and wherein the secure entity is a secure guest.9. The method of claim 7, wherein hardware presents a programinterruption to the untrusted entity indicating a need for decryption ofa secure guest page.
 10. The method of claim 9, wherein the untrustedentity issues an import instruction that provides the host absolute pageand the host virtual page.
 11. A computer program product comprising acomputer readable storage medium having program instructions embodiedtherewith, the program instructions executable to cause operationscomprising: determining, by a secure interface control of a computerthat prevents unauthorized accesses to locations in a memory of thecomputer, that a host absolute page is not previously mapped to avirtual page in accordance with securing the host absolute page; anddetermining, by the secure interface control, that a host virtual pageis not already mapped to an absolute page in accordance with securingthe host absolute page.
 12. The computer program product of claim 11,wherein the secure interface control marks the host absolute page assecure.
 13. The computer program product of claim 12, wherein the secureinterface control registers the host absolute page for use by the secureinterface control, securely decrypts the host absolute page,subsequently un-registers the host absolute page for use by the secureinterface control, and registers the host absolute page to the securedomain.
 14. The computer program product of claim 13, wherein the secureinterface control registers the host virtual address with the associatedhost absolute page to create a host-address pair for use by the secureentity, and checks the host virtual addresses match on access by thesecure entity.
 15. The computer program product of claim 13, wherein thesecure interface control locks the host absolute page for use by thesecure interface control to prevent other calls to the host absolutepage.
 16. The computer program product of claim 15, wherein the secureinterface control unlocks the host absolute page to assign a secureguest domain loaded into the memory.
 17. The computer program product ofclaim 11, wherein a secure entity accesses a secure page that has beentransparently paged-in by an untrusted entity executing on the computerand is non-secure,
 18. The computer program product of claim 17, whereinthe untrusted entity is a hypervisor, and wherein the secure entity is asecure guest.
 19. The computer program product of claim 17, whereinhardware presents a program interruption to the untrusted entityindicating a need for decryption of a secure guest page.
 20. Thecomputer program product of claim 19, wherein the untrusted entityissues an import instruction that provides the host absolute page andthe host virtual page.
 21. A system comprising: a memory; a secureinterface control of the system that prevents unauthorized accesses tolocations in the memory, wherein the system performs operationscomprising: determining, by a secure interface control of a computerthat prevents unauthorized accesses to locations in a memory of thecomputer, that a host absolute page is not previously mapped to avirtual page in accordance with securing the host absolute page; anddetermining, by the secure interface control, that a host virtual pageis not already mapped to an absolute page in accordance with securingthe host absolute page.
 22. The system of claim 21, wherein the secureinterface control marks the host absolute page as secure.
 23. The systemof claim 22, wherein the secure interface control registers the hostabsolute page for use by the secure interface control, securely decryptsthe host absolute page, subsequently un-registers the host absolute pagefor use by the secure interface control, and registers the host absolutepage to the secure domain.
 24. The system of claim 23, wherein thesecure interface control registers the host virtual address with theassociated host absolute page to create a host-address pair for use bythe secure entity, and checks the host virtual addresses match on accessby the secure entity.
 25. The system of claim 23, wherein the secureinterface control locks the host absolute page for use by the secureinterface control to prevent other calls to the host absolute page.